Hello,
No, the identifier should NOT be the same of the Pack.
You can select many packs in a "pdf serial" instance ; so the identifier IS the identifier of that "pdf serial" instance and not the packs.
The fact that the ID is the same is just a coincidence, the hasard.
Since they are incremental identifier (just like products, categories, joomla articles, menus...) you will always find 2 elements with the same ID ; even if they are two different types.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.